Wearable physiological measurement instruments exist and are used in practice, for example, in the form of wristwatches having a pulse measuring function, blood pressure meters worn on the wrist, or recently in the form of measurement instruments for determining blood oxygen saturation. Measured data for parameters to be monitored are detected by a suitable sensor, saved in the measurement instrument, and optionally processed or transmitted wirelessly to a service center, where they may be combined with other data and may be subjected to a complex analysis for an individual subject, or even for larger groups of subjects as needed, wherein the analytical results may lead to therapeutic measures or statistical conclusions.
It is important when collecting such physiological data from a wearable device, to verify whether or not, at the time of recording the measured values, the measurement instrument was located at its intended site at the body of the test subject (i.e., worn on the body, or, in a more general case, implanted permanently or temporarily within the body). If not, then the data collected may not accurately represent the subject's physiology. Such data would naturally alter the overall monitoring result in an unacceptable manner and would thus affect any statistical conclusions or statements about progress that may be derived therefrom and may even lead to misdirected treatment.